In devices using motors, which are typified by hybrid vehicles, electric vehicles, and the like, power converters are used for saving energy. For the power converters, power semiconductor modules are widely used. The power semiconductor modules include power semiconductor elements for controlling a large current.
The power semiconductor elements have a large calorific value when controlling a large current. In addition, downsizing and lightening are required for the power semiconductor modules, and the output density tends to be increased. Thus, in a power semiconductor module including a plurality of power semiconductor elements, a cooling method of the power semiconductor elements influences the power conversion efficiency.
In order to improve the cooling efficiency of a power semiconductor module, there is a power semiconductor module including a liquid-cooled cooler, in which power semiconductor elements are cooled by the cooler. The cooler of the power semiconductor module includes a metal base plate that transfers generated heat of the power semiconductor elements, a heat sink joined to a rear surface of the metal base plate, and a cooling case joined to the metal base plate and housing the heat sink, and has a structure in which a cooling liquid can flow into a space in the cooling case through an inlet and an outlet formed on the cooling case (Patent Document 1). The metal base plate, the heat sink, and the cooling case are joined by brazing (Patent Document 2).